Socketed Portal Anchors and Methods of Using Same

ABSTRACT

Anchors for securing a medical device relative to a body portal, wherein the anchors may accommodate most any implantation trajectory through the portal. Such anchors may further secure the device along any such trajectory without imparting undesirable biasing forces that may shift the device from its intended implanted location. In some embodiments, the anchor is configured as a burr hole anchor including a spherical member contained in a socket of the anchor such that orientation of the spherical member is permitted about three mutually perpendicular axes.

Embodiments of the present invention relate generally to medical devicesand, more particularly, to anchors for securing a therapy deliverydevice (e.g., a catheter or lead) within, or otherwise relative to, abody portal such as a cranial burr hole, and to systems and methodsincorporating such anchors.

BACKGROUND

Medical procedures involving insertion of a medical device into thebrain (through a burr hole formed in the skull) are used to treat avariety of medical conditions. For example, electrical stimulation ofthe brain to relieve chronic pain, or for the treatment of movementdisorders, may necessitate the implantation, via the burr hole, of anelectrode or lead. Similarly, burr holes are typically formed to allowimplantation of a therapy catheter, e.g., an intraparenchymal (IPA) orintracerebroventricular catheter, to treat various ailments.

Use of such devices to deliver therapy to the brain generally involvesthe insertion of the device into the brain through the burr hole andpositioning a distal, therapy delivery tip of the device at a desiredtarget tissue location. During a typical implantation procedure, anincision is made in the scalp to expose the patient's skull. Afterforming a burr hole through the skull, the device is inserted into thebrain. To accurately place the device, surgeons typically usestereotactic apparatus/procedures. One exemplary stereotactic apparatusis described in U.S. Pat. No. 4,350,159 to Gouda, which may be used toposition, for example, an electrode.

As one can appreciate, once an inserted device such as a catheter isproperly positioned, it is important that it be adequately immobilizedto prevent movement of its distal tip from its intended location. Suchmovement may result in undesirable lateral forces applied by theimplanted medical device to brain tissue, especially near the entrypoint (cortex). Moreover, even minimal movement of the device's distaltip may reduce therapeutic efficacy. Accordingly, reliable methods andapparatus for anchoring and securing the device relative to the burrhole are desirable.

After locating the distal tip at the target tissue location, a portionof the medical device that extends outside of the burr hole may beanchored using an anchor device. A proximal end of the medical devicemay then connect to a therapeutic source (e.g., for a catheter, to areservoir containing a therapeutic agent; for a lead, to an electricalstimulation source). For example, when the medical device is a therapycatheter, the proximal end of the therapy catheter may connect to asecond, delivery or pump catheter that is, in turn, coupled to animplantable pump containing the therapeutic agent. As a result, theagent may be delivered through the delivery catheter and the therapycatheter to the desired target tissue location within the patient.

Increasingly, surgeons desire access to the brain via devicetrajectories that are angled relative to the burr hole. That is, somesurgeries may benefit from insertion of the medical device into thebrain at an angle that is canted from (e.g., not aligned with) an axisnormal to the skull surface at the burr hole. Many existing burr holeanchors, however, are configured to grip or secure the medical deviceassuming that its orientation is normal to the skull surface. In thecase of an angled implant trajectory, such anchors may impart clampingforces that potentially bias the device away from its original implanttrajectory, and thus bias the therapy delivery tip away from theintended target tissue location. This result may be amplified withincreased trajectory angle, stiffer medical devices, and shallowerinsertion depths.

SUMMARY

The present invention may overcome these and other issues by providing,in one embodiment, a sub-dermal anchor configured to secure a medicaldevice implanted via a portal formed in a mammalian body. The anchor mayinclude a base configured to secure to tissue surrounding the portal,wherein the base has an upper side, lower side, outer edge, and inneredge. The inner edge may define an opening passing between the upper andlower sides, wherein the opening forms a socket. An elastomericretention member may also be provided, wherein the retention memberincludes a spherical surface. The retention member may be configured tobe received within the socket such that the retention member may rotatetherein about three mutually perpendicular axes. The retention memberdefines a bore formed therethrough, the bore configured to permitpassage of the medical device through the base from the upper side tothe lower side. The retention member is positioned within the socketsuch that an uppermost surface of the retention member is at anelevation below the upper side of the base.

In another embodiment, a burr hole anchor is provided and configured tosecure a medical device implanted through a burr hole. The anchor mayinclude a base configured to secure to bone surrounding the burr hole,the base having an upper side, lower side, outer edge, and inner edge,the inner edge defining an opening passing between the upper and lowersides, wherein the opening forms a socket. Also included is anelastomeric spherical member configured to be received within the socketsuch that the spherical member may rotate therein. The spherical membermay define a bore formed therethrough, the bore configured to permitpassage of the medical device through the base from the upper side tothe lower side. The spherical member is configured to immobilize themedical device via application of a radial compression force applied tothe medical device.

In another embodiment, a method for anchoring a medical device relativeto a body portal of a patient is provided. The method may include:aligning a guide cannula with the body portal such that a trajectory ofthe guide cannula intersects a target tissue location within thepatient; and inserting a distal tip of the guide cannula through a boreformed in a portal anchor and sliding the portal anchor along the guidecannula. The anchor may include a base configured to secure to tissuesurrounding the portal, wherein the base includes an upper side, lowerside, outer edge, and inner edge. The inner edge may define an openingpassing between the upper and lower sides, the opening forming a socket.An elastomeric spherical member may also be provided and configured tobe received within the socket such that the spherical member may rotatetherein about three mutually perpendicular axes, wherein the sphericalmember may define the bore for receiving the guide cannula. The methodfurther includes: positioning the guide cannula so that the distal tipis inside the body portal; sliding the anchor towards the distal tip ofthe guide cannula until the base of the anchor reaches the tissuesurrounding the body portal; rotating the spherical member relative tothe base until the base is flush with the tissue surrounding the bodyportal; and attaching the base to the tissue.

In yet another embodiment, an infusion system is provided including atherapy catheter implantable through a burr hole, wherein the therapycatheter includes a therapy delivery end configured to be positioned ata target tissue location. A delivery catheter is also provided andoperable to deliver a therapeutic agent, from a source containing thetherapeutic agent, to the therapy catheter. A connector configured tofluidly couple the therapy catheter with the delivery catheter may alsobe included. The system may also include an anchor including a baseconfigured to secure to bone surrounding the burr hole, wherein the basehas an upper side, lower side, outer edge, and inner edge, the inneredge defining an opening passing between the upper and lower sides,wherein the opening forms a socket. The anchor may further include aspherical member configured to be received within the socket such thatthe spherical member may rotate therein about three mutuallyperpendicular axes. The spherical member may define a bore therein, thebore configured to receive both a first end of the therapy catheter anda first end of the connector when the first end of the connector isfluidly coupled to the therapy catheter.

In still yet another embodiment, an infusion system is provided thatincludes a therapy catheter implantable through a burr hole, wherein thetherapy catheter includes a therapy delivery end configured to bepositioned at a target tissue location. A delivery catheter may also beincluded and operable to deliver a therapeutic agent, from a sourcecontaining the therapeutic agent, to the therapy catheter. A connectormay be provided to fluidly couple the therapy catheter with the deliverycatheter. The system may also include an anchor having a base configuredto secure to bone surrounding the burr hole. The base may include anupper side, lower side, outer edge, and inner edge, the inner edgedefining an opening passing between the upper and lower sides, whereinthe opening forms a socket. The anchor may further include anelastomeric spherical member configured to be received within the socketsuch that the spherical member may rotate therein. The spherical membermay define a bore formed therethrough, the bore configured to permitpassage of the therapy catheter through the base from the upper side tothe lower side, wherein the spherical member is configured to immobilizethe therapy catheter via application of a radial compression forceapplied to the therapy catheter.

The above summary is not intended to describe each embodiment or everyimplementation of the present invention. Rather, a more completeunderstanding of the invention will become apparent and appreciated byreference to the following Detailed Description of Exemplary Embodimentsand claims in view of the accompanying figures of the drawing.

BRIEF DESCRIPTION OF THE VIEWS OF THE DRAWING

The present invention will be further described with reference to thefigures of the drawing, wherein:

FIG. 1 illustrates an exemplary implantable infusion system, the systemincluding an anchor system in accordance with one embodiment of theinvention;

FIGS. 2-3 illustrate diagrammatic views of a trajectory of an implantedmedical device in two orthogonal planes, wherein:

FIG. 2 illustrates the device trajectory when viewed normal to a first(e.g., sagittal) plane; and

FIG. 3 when viewed normal to a second, intersecting and orthogonal(e.g., coronal) plane;

FIG. 4 is a perspective view of an portal anchor (e.g., burr holeanchor) in accordance with one embodiment of the invention;

FIG. 5 is a section view taken along line 5-5 of FIG. 4;

FIG. 6 is a perspective view of a connector of the anchor of FIG. 4;

FIG. 7 is a section view taken along line 7-7 of FIG. 4;

FIG. 8 is a bottom perspective view of the anchor of FIG. 4;

FIG. 9 is a section view taken along line 9-9 of FIG. 4;

FIG. 10 is a section view similar to FIG. 5 but illustrating an anchorin accordance with another embodiment of the invention;

FIG. 11 is a section view like FIG. 9, but illustrating the embodimentof FIG. 10;

FIG. 12 is a bottom perspective view of the embodiment of FIG. 10;

FIG. 13 is a top perspective view of an anchor in accordance with yetanother embodiment of the invention;

FIG. 14 is a section view taken along line 14-14 of FIG. 13;

FIG. 15 is an exploded view of a retention member, e.g., sphericalmember, of the anchor of FIGS. 13-14;

FIG. 16 is a bottom perspective view of the anchor of FIG. 13;

FIG. 17 is a partial section view (e.g., cap removed) taken along line17-17 of FIG. 13;

FIGS. 18-23 illustrate diagrammatically an exemplary method for usingthe anchors illustrated in the previous figures, wherein:

FIG. 18 illustrates initial attachment of the anchor to a guide cannula;

FIG. 19 illustrates movement of the anchor to a tissue (e.g., skull)surface;

FIG. 20 illustrates attachment of the anchor to the tissue;

FIG. 21 illustrates immobilization of a retention member of the anchor;

FIG. 22 illustrates insertion of the medical device; and

FIG. 23 illustrates removal of the guide cannula;

FIG. 24 illustrates an anchor in accordance with still anotherembodiment of the invention:

FIG. 25 illustrates a section view taken along line 25-25 of FIG. 24;

FIG. 26 is a perspective view of a connector for use with the anchor ofFIG. 24;

FIG. 27 is a perspective view illustrating the anchor of FIG. 24 beforeimmobilization of a retention member of the anchor;

FIG. 28 is a section view illustrating the anchor of FIG. 24 afterimmobilization of the retention member;

FIGS. 29-34 illustrate an exemplary diagrammatic method for using theanchor illustrated in FIG. 24-28 to anchor a therapy catheter, wherein:

FIG. 29 is a partial perspective view illustrating an exemplary methodof securing a guide cannula relative to a spherical member of theanchor;

FIG. 30 shows removal of the guide cannula after insertion of thetherapy catheter;

FIG. 31 is a partial perspective view illustrating how the therapycatheter may be secured relative to the spherical member once the guidecannula is retracted;

FIG. 32 is a section view illustrating coupling of a connector to thetherapy catheter;

FIG. 33 is a perspective view illustrating the anchor after theconnector and therapy catheter are coupled; and

FIG. 34 is a perspective view illustrating coupling of the connectorwith a delivery catheter;

FIG. 35 illustrates an anchor in accordance with still yet anotherembodiment of the invention;

FIG. 36 is a bottom perspective view of the anchor of FIG. 35;

FIG. 37 is a section view taken along line 37-37 of FIG. 35;

FIG. 38 is an upper perspective view of an anchor in accordance with yetstill another embodiment of the invention;

FIG. 39 is a section view taken along line 39-39 of FIG. 38;

FIG. 40 is a partial (cap and medical device not shown) perspective viewof the anchor of FIG. 38 in an expanded configuration;

FIG. 41 is a partial perspective view of the anchor of FIG. 38 in alocked configuration;

FIG. 42 is a bottom perspective view of the anchor of FIG. 40 (withmedical device shown);

FIGS. 43-49 illustrate diagrammatically an exemplary method for usingthe anchor shown in FIGS. 38-42, wherein:

FIG. 43 illustrates initial attachment of the anchor to a guide cannula;

FIG. 44 illustrates movement of the anchor to a tissue (e.g., skull)surface;

FIG. 45 illustrates initial attachment of the anchor to the tissue;

FIG. 46 illustrates removal of the guide cannula after insertion of amedical device;

FIG. 47 illustrates immobilization of a retention member of the anchor;

FIG. 48 illustrates final attachment of the anchor to the tissue andattachment of an optional cap; and

FIG. 49 illustrates a bottom perspective view of the optional cap;

FIG. 50 is an upper perspective view of an anchor in accordance withstill yet another embodiment of the invention, the anchor shown with afirst clip installed;

FIG. 51 is an upper perspective view of the anchor of FIG. 50 showingthe first clip removed;

FIG. 52 is an upper perspective view of the anchor of FIG. 50 afterimplanting of a medical device and initial attachment of the anchor totissue;

FIG. 53 is an upper perspective view of the anchor of FIG. 52 afterfurther removing the first clip;

FIG. 54 is an upper perspective view of the anchor of FIG. 53 afterattachment of a second clip and final attachment of the anchor to thetissue;

FIG. 55 is an upper perspective view of the anchor of FIG. 54 afterremoval of the second clip, routing of the medical device, andattachment of an optional cap;

FIG. 56 is an upper perspective view of a catheter anchor in accordancewith yet still another embodiment of the invention; and

FIG. 57 is a perspective view of a catheter connector for use with theanchor of FIG. 56.

The figures are rendered primarily for clarity and, as a result, are notnecessarily drawn to scale. Moreover, various structure/components,including but not limited to fasteners, electrical components (wiring,cables, etc.), and the like, may be shown diagrammatically or removedfrom some or all of the views to better illustrate aspects of thedepicted embodiments, or where inclusion of such structure/components isnot necessary to an understanding of the various exemplary embodimentsof the invention. The lack of illustration/description of suchstructure/components in a particular figure is, however, not to beinterpreted as limiting the scope of the invention in any way.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

In the following detailed description of illustrative embodiments of theinvention, reference is made to the accompanying figures of the drawingwhich form a part hereof and in which are shown, by way of illustration,specific embodiments in which the invention may be practiced. It is tobe understood that other embodiments may be utilized and structuralchanges may be made without departing from the scope of the presentinvention.

Embodiments of the instant invention may be directed to body portalanchor devices and assemblies and to corresponding body portal anchorsystems and methods for securing a medical device such as a therapycatheter or stimulation lead relative to a body portal. For example,exemplary anchors described herein may be configured to secure a therapydevice such as an IPA therapy catheter routed through a cranial burrhole. Such embodiments may further provide for connection of the therapycatheter with a delivery catheter that is fluidly connected to a therapysource. While embodiments described herein may find use in acutetreatment, they are particularly advantageous for long-termimplantation, e.g., lasting several weeks or longer. Accordingly,devices in accordance with embodiments of the instant invention providea low profile, allowing them to be located sub-dermally, potentially foran indefinite period of time, e.g., seven years or more.

Systems in accordance with embodiments of the present invention maypermit substantial isolation of the medical device (e.g., therapycatheter or lead) from forces that may act outside of the body portal,e.g., forces acting upon the delivery catheter connected to the therapycatheter. Moreover, systems, anchors, and methods in accordance withembodiments of the present invention may accommodate implantationtrajectories along most any axis through the burr hole. That is, anchorslike those described herein may receive and secure the medical devicealong most any trajectory (e.g., normal to the skull or otherwise) andmay further secure the device along such a trajectory without impartingexcessive biasing forces that may shift the device from its implantedlocation or apply lateral pressure against tissue (e.g., against thecortex).

While exemplified herein in the context of burr hole anchors andcorresponding infusion/electrical stimulation systems, anchors andsystems in accordance with embodiments of the present invention may beadvantageous for other applications. In fact, while described hereinwith reference to the treatment of neurological disorders, embodimentsof the present invention may find use in most any system (e.g., medicalor otherwise) that would benefit from portal anchoring of an elongatemember.

It is noted that the terms “comprises” and variations thereof do nothave a limiting meaning where these terms appear in the accompanyingdescription and claims. Further, “a,” “an,” “the,” “at least one,” and“one or more” are used interchangeably herein. Moreover, relative termssuch as “left,” “right,” “front,” forward,” “aft,” “rear,” “rearward,”“top,” “bottom,” “side,” “upper,” “lower,” “above,” “below,”“horizontal,” “vertical,” and the like may be used herein and, if so,are from the perspective observed in the particular figure (or asobserved when the apparatus is in a typical use orientation). Theseterms are used only to simplify the description, however, and not tolimit the scope of the invention in any way.

With reference to the drawing, wherein like reference numerals designatelike parts and assemblies throughout the several views, FIG. 1diagrammatically illustrates an exemplary implantable medical systemsuch as a brain infusion system 100 as it may be configured during use,e.g., implantation. Exemplary embodiments of the components describedand illustrated herein may be sized for use with burr holes typical inhuman and other mammalian (e.g., primate) applications. For example, inone embodiment, a diameter of the burr hole 110 (see, e.g., FIG. 2) maybe anywhere from about 6 millimeters (mm) to about 14 mm in diameter.However, such a configuration is not limiting as exemplary anchors couldbe scaled to accommodate most any size portal without departing from thescope of the invention.

The exemplary infusion system 100 may include a therapy source 106, andan anchor system 201. The anchor system may include a cranial burr holeanchor device or assembly (referred to herein as “anchor 200”) and, insome embodiments, a first medical tube, e.g., an intra-cranial IPAtherapy catheter 102. The therapy catheter 102 may be partiallyimplanted within a mammalian (e.g., human) brain 116 such that a distal,therapy delivery tip or end 108 is located at a target tissue location119 in the brain.

To assist with placement of the therapy catheter 102, a stereotacticapparatus (diagrammatically illustrated by reference number 103) as isknown in the art may be utilized (see, for example, U.S. Pat. Pub. No.2012/0083742 to Nelson). In the illustrated example, the therapycatheter 102 is implanted through a body portal, e.g., through a burrhole 110 (the burr hole is located underneath a burr hole anchor 200 inFIG. 1; but see FIGS. 2 and 5). The burr hole 110 may be formed intissue (e.g., the bone forming the skull 111, which is shown underneaththe scalp 109, the scalp being shown peeled back to provide access tothe skull in FIG. 1).

Once the catheter 102 is accurately implanted through the burr hole inthe skull (i.e., once the therapy delivery tip 108 is positioned at thepredetermined target tissue location 119 in the brain 116), a proximalportion of the catheter 102 (the portion extending outside the burrhole) may be anchored with an anchor (anchor 200) in accordance withembodiments of the present invention.

A first end 112 of the therapy catheter 102 may be routable through theanchor 200. In the illustrated embodiment, the first end 112 of thetherapy catheter 102 (after disconnecting from the stereotacticapparatus and trimming to an appropriate length) may be operativelyconnected to a corresponding first end 114 of a feed or deliverycatheter 104 (e.g., via a connector associated with the anchor,exemplary embodiments of which are described below) of the system100/anchor system 201.

The delivery catheter 104 may have a second end 105 coupled to a therapysource or reservoir (e.g., an implantable infusion pump 106 such as aSynchroMed® II programmable infusion pump distributed by Medtronic,Inc., of Minneapolis, Minn. USA) containing a volume of the therapeuticagent. While described and illustrated herein utilizing an implantableinfusion pump, this configuration is not limiting. For example, otherembodiments may replace the pump with most any internal or externalmedicament delivery device, e.g., syringe, drip bag, etc.

The infusion system 100 may, in one embodiment, be configured to delivera therapeutic agent for the treatment of a chronic ailment, e.g.,convection-enhanced delivery (CED) of a therapeutic agent for thetreatment of Huntington's disease. The therapeutic agent is delivered,via the catheters 102 and 104, from the pump 106 to the target tissuelocation 119 of the brain 116. This application is not limiting,however, as the system may be configured to deliver other therapeuticagents (e.g., such as for the treatment of Parkinson's or Alzheimer'sdisease) to the brain or to most any other region of the body.

As used herein, “therapeutic agents” may be a generic term referring toa fluid containing pharmaceutical compositions, genetic materials,biologics, and other substances. Pharmaceutical compositions mayinclude, for example, antispasmodics, pain medications, chemotherapeuticagents, and the like. Genetic materials include substances intended tohave a direct or indirect genetic therapeutic effect such as geneticvectors, genetic regulator elements, genetic structural elements, DNA,and the like. Biologics include substances that are living matter orderived from living matter intended to have a therapeutic effect such asstem cells, platelets, hormones, biologically produced chemicals, andthe like. Other substances may include those that do not have a directtherapeutic effect such as, saline solutions, fluoroscopy agents,disease diagnostic agents, and the like. Accordingly, unless otherwisenoted, the terms “therapeutic agent,” “therapeutic substance,” “drug,”or “fluid” may be used interchangeably herein and may include most anytherapeutic, diagnostic, or other substance that is delivered using theimplantable systems and methods described herein.

Once again, while described above in the context of catheterimplantation, the system 100, including the anchor 200, could also beconfigured to anchor an electrical element such as a stimulation lead.That is, the system could be an electrical stimulation lead system 100in which a lead 102 is implanted such that its distal end 108 ispositioned at the desired target tissue location 119. A proximal end 112of the lead 102 could then, after disconnection from the stereotacticapparatus 103, be tunneled beneath the scalp 109 and connected to anelectrical stimulation source 106 (in this embodiment, the lead 102 mayconnect to an intermediate extension 104 that, in turn, connects to theelectrical stimulation source 106).

With this general overview, the following description addresses variousembodiments and aspects of exemplary anchors systems, as well as methodsfor using the same. While these embodiments may be described with somedegree of particularity, they are nonetheless exemplary. That is, thoseof skill in the art will recognize that other embodiments are certainlypossible without departing from the scope of the invention. Moreover,unless clearly stated otherwise, the actual medical device describedand/or illustrated in conjunction with any specific embodiment hereinmay be either a therapy catheter or an electrical lead. As a result, theterms “medical device” (or “device”), “therapy catheter” (or“catheter”), and “electrical lead” (or “lead”) may be used herein torefer to most any elongate member.

FIGS. 2 and 3 are exemplary diagrammatic illustrations of the medicaldevice 102 implanted through the burr hole 110 formed in the skull 111(anchor 200 removed for clarity in these views), with FIG. 2 showing aview looking normal to a first (e.g., sagittal) plane and FIG. 3 showinga view looking normal to a second intersecting, orthogonal (e.g.,coronal) plane. As clearly indicated in these views, thestereotactically-guided trajectory 118 (which may also be referred toherein as an “axis” 118) of the device 102 may be selected to intersectthe target tissue location 119 within the brain 116. As furtherillustrated in these views, the trajectory 118 may be along an axis thatis slanted relative to a line 122 normal to the tissue (e.g., slantedrelative to a line normal to the skull bone) surrounding the burr hole.That is, the trajectory 118 may be oriented such that it is neithercoaxial nor parallel to an axis (the axis being coincident andco-identified with line 122) of the burr hole 110.

For instance, when viewed normal to the first (e.g., sagittal) plane asshown in FIG. 2, the trajectory axis 118 is slanted at an angle 120 fromthe axis 122. Moreover, the trajectory 118 may also be slanted, relativeto the axis 122, when viewed normal to the second (e.g., coronal) planeat an angle 121. That is to say, the trajectory 118 may be skewed fromnormal relative to one or both of these mutually perpendicular planes.Anchors in accordance with embodiments of the present invention areconfigured to secure the medical device, without undesirably impartinganchor forces that could ultimately bias the therapy delivery tip 108away from the target tissue location 119. This advantage may be realizedregardless of whether the device trajectory 118 is parallel to the axis122, or is instead slanted (in one or both planes) relative to the axissuch as illustrated in FIGS. 2 and 3. While not wishing to be bound toany particular orientation, the angles 120 and 121 could be about 30degrees or less, e.g., 25 degrees or less.

FIGS. 4-9 illustrate various views of the anchor system 201 includingthe burr hole anchor 200 in accordance with one exemplary embodiment ofthe invention. With reference to FIG. 4, the anchor 200 may include anannular base 202 that may be positioned to surround the burr hole 110(covered by the anchor in FIG. 4, but see FIG. 5). The anchor 200 (e.g.,the base 202) is operable to secure to the tissue, e.g., to an outersurface of the bone (skull 11), surrounding the burr hole 110 via anyacceptable method. In the illustrated embodiment, the base 202 issecured with bone screws 203 extending through openings (e.g., holes206) formed through the base 202 and threaded into the skull 111.

The base 202 may include an upper side 207, a lower side 209, aperipheral or outer edge 211, and an inner edge 213. The inner edge 213may define an opening 208 passing through the base 202 between the upperand lower sides 207 and 209, wherein the inner edge further defines asocket 210 as is also shown in FIGS. 5 and 8-9. The socket 210 may beconfigured to receive therein a retention member that forms or otherwiseincludes a convex or spherical surface 216 (see also FIG. 5). In theembodiment illustrated in FIGS. 4-9, the retention member may beconfigured as a ball-shaped or spherical member 214, while in otherembodiments the retention member may merely incorporate one or moreportions that define a spherical surface. As used herein, the term“spherical member” includes any retention member forming orincorporating a spherical surface, whether or not the retention memberis actually ball-shaped.

The retention member (e.g., spherical member 214) is configured to bereceived within the socket 210 such that the retention member isoperable, under certain circumstances, to rotate therein about threemutually perpendicular axes represented in FIG. 4 by axes x, y, and z.

The spherical member 214 may define a bore 218 formed therethrough. Thebore 218 is configured to permit passage of the medical device (e.g.,catheter or lead 102 as shown in FIG. 5) through the base 202 from theupper side 207 to the lower side 209. Moreover, in the illustratedembodiment, the spherical member 214 is positioned within the socket 210such that an uppermost surface 215 of the retention member is at anelevation below the upper side 207 of the base as best seen in FIG. 5.As with the other embodiments described herein, the anchor 200 mayprovide a low profile as also shown in FIG. 5. This is partiallyaccomplished by recessing the spherical member 214 into the burr hole asshown. While not wishing to be bound to any particular height, theanchor may, in one embodiment, extend above the surface of the skull 111a distance of about 2-3 mm, e.g., about 2.5 mm.

As shown in FIG. 5, the opening 208 formed in the base 202 may bepositioned to align coaxially with the burr hole 110. The upper side 207of the base 202 may also define a passage, e.g., groove 220, extendingfrom the inner edge 213 to and through the outer edge 211. The groove220 may define a channel configured to receive therein the medicaldevice 102 during device anchoring. For example, when used with atherapy catheter 102, the groove 220 may receive therein the proximalend 112 of the therapy catheter 102. The groove 220 may be configured inmost any acceptable manner that provides a passage or channel extendingfrom the opening 208 through the peripheral or outer edge 211. In theillustrated embodiment, the groove 220 is configured as a relativelyopen-faced trough as shown in FIGS. 4 and 5. The groove 220 may befurther defined by an enlarged section or relief 222, the purpose ofwhich is explained in more detail below.

While shown herein as a trough-like groove 220 (see, e.g., FIG. 5), thepassage could alternatively pass completely through the base (form aslot extending between the upper and lower sides) as shown, for example,with slot 820 in FIG. 51.

In addition to selectively receiving the catheter 102, the trough-likegroove 220 may also selectively receive therein a tubular pin orconnector 204, which is illustrated separately in FIG. 6. The connector204 is configured for use with the anchor 200 when the latter is used tosecure a therapy catheter (i.e., the connector may not be required whenthe medical device 102 is configured as an electrical lead).

As shown in FIG. 6, the connector 204 may include a first end 226defining a therapy tip, and an opposite or second end 228 defining adelivery tip. The connector 204 may further include an enlarged centralportion 230 between the first and second ends. The first and second ends226, 228 (e.g., the therapy tip and the delivery tip) may be configuredfor insertion into lumens of, respectively, the therapy catheter 102 andthe delivery catheter 104. The shape and size of the first and secondends of the connector 204, as well as the size and material of thecatheters, may be selected to produce a relatively secure and leak-freeconnection between the catheters and the connector when joined. Theconnector 204 is hollow to permit passage of fluid from the deliverycatheter 104 to the therapy catheter 102.

The central portion 230 of the connector 204 may further include one ormore retaining elements, which in one embodiment, are configured asdiverging protrusions 232. The protrusions 232 may be designed to engagethe relief 222 of the groove 220 as shown in the section view of FIG. 7(some anchor structure removed from this view for clarity). That is (asfurther described below), once the therapy catheter 102 is connected tothe first end 226 of the connector 204, the connector may be placed intothe groove 220 and pushed (downwardly in FIG. 7) until the protrusions232 deflect and engage overhanging portions 234 of the base within therelief 222, e.g., with a snap-fit. Once the connector 204 is received inthis manner, it is captivated or immobilized, relative to the base 202,from axial, transverse, and rotational movement. Such immobilization mayprevent, or at least reduce, forces from being transmitted between thedelivery catheter 104 and the therapy catheter 102 that could dislodgethe therapy delivery tip 108.

As used herein, the term “immobilize” and its variations refers tosecuring a first member to one or more second members such that littleor no relative movement occurs between the first and second members.Those of skill in the art will realize that, for a variety of reasons(e.g., tolerances of parts), some minor relative movement may stilloccur between the members, but such movement is minimized and of littleor no consequence to the intended operation of the immobilized member.

While most any biocompatible material is suitable, the base 202 may, inone embodiment, be made from a moldable thermoplastic (e.g., polysulfoneor polyetheretherketone (PEEK)) or metal such as grade 2 or grade 5Titanium. The connector 204 may be made of the same or similar material.The retention member (e.g., spherical member 214) however, for reasonsthat will become apparent, may be made of a softer elastomeric materialsuch as silicone or urethane (e.g., 55D urethane).

FIGS. 5 and 8-9 illustrate additional details regarding the exemplaryretention member (e.g., spherical member 214) and its interaction withthe socket 210 of the base 202. As evident in these views, the inneredge 213 that forms the socket 210 may itself form a concave orspherically-shaped surface 212 such that the spherical member 214 isreceived and retained therein. To accommodate the spherical member 214,the inner edge 213 may include two or more (e.g., four) downwardlyprotruding segments 236 (see FIG. 8) that at least partially form thesocket 210. The segments 236 may be sufficiently deflectable to permitassembly (i.e., insertion of the spherical member 214 into the base 202)of the anchor 200 during manufacture/assembly.

In the illustrated embodiments, the socket 210 is designed toaccommodate the spherical member 214 with clearance or slightinterference such that the spherical member may rotate within the socketduring the surgical implant process. That is, the socket 210 may besized such that the spherical member 214 may rotate therein about thethree mutually perpendicular axes (see, e.g., axes x, y, and z of FIG.4). As a result, the spherical member 214 (and thus the bore 218) may beoriented as needed, relative to the base 202, during implantation andthe spherical member may stay aligned with the trajectory 118 duringfixation of the base 202 to the skull 111. However, the anchor 200 mayalso include a lock member to lock the spherical member 214 relative tothe base 202 once the desired trajectory of the catheter is set. In theillustrated embodiment, the lock member may be configured as a fastener(e.g., a bone screw 238) that passes through the base 202 (e.g., withclearance) and protrudes therefrom into the socket 210 as best shown inFIGS. 8 and 9. When the screw 238 is tightened, it penetrates, e.g.,threads into or “taps,” the spherical member 214 as shown in FIG. 9.Stated alternatively, once the catheter 102 is implanted aid and thebase 202 is secured to the skull 111 (e.g., via the bone screws 203 (seeFIG. 4), the spherical member 214 may be immobilized relative to thebase 202 by tightening the screw 238. A length of the screw 238 may beselected such that its distal tip (the tip contacting/penetrating thespherical member) cannot extend into the bore 218 of the sphericalmember 214 even when the screw 238 is fully tightened.

The retention member may have various constructions. For instance, inthe embodiment of FIGS. 4-9, the bore 218 may be formed (e.g., molded)as either a constant diameter extending through the spherical member214, or alternatively, as a stepped diameter as seen most clearly inFIG. 5. The stepped diameter may be used to control the area ofengagement between the spherical member 214 and the medical device(e.g., catheter 102). For example, in the illustrated embodiment, thestepped diameter provides two discrete circumferential areas 224 ofcontact (e.g., the areas 224 define continuous rings of contact) betweenthe spherical member 214 and the catheter, although any number ofdiscrete contact areas is possible. These contact areas 224 apply acompression radial force to the catheter 102 (and, as described below,to a guide cannula used when inserting the catheter) to secure thecatheter relative to the spherical member 214. In other embodiments, theareas 224 may be segmented or broken such that the area in contact withthe medical device is discontinuous.

The bore 218 may further include a chamfer or radius 240 near theuppermost surface 215 as shown in FIG. 5 to reduce the occurrence ofpinching or kinking of the medical device and to assist with placing thecatheter 102 into bore 218 and then into the groove 220. As will beobserved with this and other embodiments described herein, thecircumferentially applied radial compression of the medical device 102(e.g., applied by the bore 218 of the spherical member 214) may, in someapplications, be considered advantageous as compared to anchors thatimmobilize the medical device via opposing and relatively rigid (e.g.,metal or plastic) engagement members.

FIGS. 10-12 illustrate an alternative embodiment of the anchor 200 thatis, with the exception of the construction of the retention member,identical to the anchor already described herein above. For the sake ofbrevity, description of those aspects common to both embodiments willnot be repeated herein.

As shown in FIG. 10, a retention member, e.g., spherical member 314, mayreplace the spherical member 214 within the anchor 200. Like thespherical member 214, the spherical member 314 is generally ball-shapedand includes a spherical surface 316 and a bore 318. The sphericalmember 314 could form a simple chamfer or radius 240 like the radius 240described above. Alternatively, it could incorporate a slot or recess340 that may intersect the bore 318 and extend away therefrom in acircumferential direction (e.g., it may extend away from one or bothsides of the bore). The recess 340 could be beneficial to further ensurethat the medical device 102 is not kinked or occluded by the edge of thebore 318 when the device is bent over and placed into the groove 220.

The spherical member 314 may also differ from the spherical member 214in the construction of the bore 318. As shown in FIG. 10, the bore 318is defined, at least in part, by a separate retaining sleeve 350 thatdefines a contact area 324 between the spherical member and the medicaldevice (e.g., catheter 102) to frictionally engage the medical device.An optional sleeve cap 352 may also be included to assist with retainingthe sleeve 350 within the spherical member 314.

To accommodate the sleeve 350 and cap 352, the spherical member 314 maybe created with an oversized diameter to receive the sleeve. Thediameter may be stepped (counterbored from below) as shown in FIG. 10 todefine retaining portions, e.g., a land or stop surface 354, that assistwith locating and retaining the sleeve 350. Once the sleeve 350 islocated, the sleeve cap 352 may be attached at the lower end of themember 314. To ensure that the sleeve 350 and cap 352 remain in place,one or both components may be secured by any acceptable methodincluding, but not limited to, sonic welding, interference fit,adhesive, and thermal bonding techniques.

The spherical member 314 may offer certain advantages. For example, asingle spherical member 314 could accommodate sleeves (and caps) havinga variety of inner diameters. As a result, one spherical member could beused with different sleeves 350 to provide for medical devices ofdifferent materials and/or diameters. Moreover, by utilizing theseparate sleeve 350, a second material of the sleeve (e.g., silicone)may be optimized for frictional engagement and retention of the medicaldevice 102, while a first material of the outer spherical surface 316(e.g., urethane or some other material potentially different than thefirst material) may be optimized to interact, e.g., rotate moresmoothly, with the socket 210 of the base 202 and/or resist undesirabledeformation of the member 314 when penetrated by the screw 238 (see FIG.11). FIG. 11 is a section view illustrating the spherical member 314once the lock member (e.g., screw 238) is actuated. Moreover, FIG. 12illustrates a bottom view illustrating the sleeve cap 352.

FIGS. 13-17 illustrate an anchor system 401 having a cranial burr holeanchor 400 in accordance with yet another embodiment of the invention.Those of skill in the art will recognize similarities between the anchor400 and those described elsewhere herein (e.g., the anchor 200), andthat components of the different embodiments described and illustratedherein may be substituted to yield yet additional embodiments withoutdeparting from the scope of the invention.

Unlike the anchor 200, the anchor 400 is described and illustrated inthe context of an electrical lead 102. However, as already stated, suchan application is exemplary only and the anchor 400 could be used toanchor a therapy catheter without departing from the scope of theinvention.

With reference primarily to FIGS. 13 and 14, the anchor 400 may againinclude an annular base 402 positionable to surround the burr hole 110(covered by the anchor in FIG. 13, but see FIG. 14). The anchor 400(e.g., the base 402) is operable to secure to the tissue, e.g., to anouter surface of the bone (skull 111), surrounding the burr hole 110 viaany acceptable method. In the illustrated embodiment, the base 402 issecured with bone screws 403 extending through openings (e.g., holes406) formed through the base 402 and threaded into the skull 111. In theillustrated embodiment, the holes 406 are formed in portions 423 of thebase 402 that protrude outwardly as shown in FIG. 13. Such aconstruction may benefit from flex grooves 425 that permit the portions423 to flex as the base 402 is attached to the skull 111 with the screws403.

The base 402 may include an upper side 407, a lower side 409, aperipheral or outer edge 411, and an inner edge 413. The inner edge 413may define an opening 408 passing through the base 402 between the upperand lower sides 407 and 409, wherein the inner edge further defines asocket 410 as is also shown in FIGS. 16 and 17. An optional cap or cover405 may attach to the base 402 to cover the opening 408 after themedical device 102 is implanted.

The socket 410 may be configured to receive therein a retention memberthat forms or otherwise includes a convex or spherical surface 416 (seeFIG. 14). In the embodiment illustrated in FIGS. 13-17, the retentionmember may once again form a ball-shaped or spherical member 414. Theretention member (e.g., spherical member 414) is configured to bereceived within the socket 410 such that the retention member isoperable, under certain circumstances, to rotate therein about threemutually perpendicular axes (see, e.g., axes x, y, and z of FIG. 4).

As with the spherical members 214 and 314 described above, the sphericalmember 414 may include a bore 418 formed therethrough. The bore 418 isconfigured to permit passage of the medical device (e.g., catheter orlead 102) through the base 402 from the upper side 407 to the lower side409. Moreover, once again, the spherical member 414 may be positionedwithin the socket 410 such that an uppermost surface 415 of theretention member is at an elevation at or below the upper side 407 ofthe base as perhaps best illustrated in FIGS. 14 and 17. Such a lowprofile construction may accommodate a relatively flat cover 405 asshown.

As shown in FIG. 14, the opening 408 may again be positioned to aligncoaxially with the burr hole 110. Moreover, the upper side 407 of thebase 202 may define a passage, e.g., groove 420, extending from theinner edge 413 to and through the outer edge 411. The groove 420 mayagain define a passage configured to receive therein the lead 102 asshown in FIGS. 13-14. As connection to a separate device is notnecessary with the lead 102, the groove 420 may be devoid of featuresuseful to accommodate a connector like the connector 204 describedelsewhere herein. The groove 420 may be configured in most anyacceptable manner that provides a passage or channel extending from theopening 408 through the peripheral or outer edge 411. In the illustratedembodiment, the groove 420 is again configured as a relativelyopen-faced trough as shown in FIG. 13. As with the anchor 200, most anybiocompatible material is suitable for the base 402 and cap 405, e.g.,moldable thermoplastic (e.g., polysulfone or PEEK) or metal such asgrade 2 or grade 5 Titanium.

Once again, while illustrated with the lead 102, the anchor 400 may alsobe applicable to a therapy catheter 102 (although connection to adelivery catheter may not be accommodated within the base 402).

The spherical member 414 and associated socket 410 of the base 402function in a manner substantially similar to the spherical members 214and 314 already described herein. However, the actual construction ofthe spherical member 414 may vary in comparison as illustrated in FIG.15. As stated elsewhere herein, the spherical members described herein(e.g., 214, 314, 414, and those described subsequently), may besubstituted for one another without departing from the scope of theinvention.

As shown in FIG. 15, the bore 418 of the spherical member 414 isdefined, at least in part, by a separate cylindrical retaining sleeve450 that defines a contact area 424 (see FIG. 14) between the sphericalmember 414 and the medical device (e.g., lead 102). Unlike the sphericalmember 314, however, the spherical member 414 is constructed as twomating semi-spherical halves 452 that join to form a unified,ball-shaped member. To assist with aligning the halves 452, each halfmay include a recess 456 and a tab 458 (only one half visible in FIG.15, but see FIG. 17). As shown in FIG. 14, the sleeve 450 (like thesleeve 350 and some of the other retention members described below) maypermit the bore 418 to apply its radial compression force to the medicaldevice 102 (e.g., frictionally receive the medical device) over asubstantial portion of a length of the bore.

To accommodate and contain the sleeve 450, a passageway formed throughthe spherical member 414 (the two halves 452 when assembled) may beformed with an oversized diameter near its center that steps or reducesnear each end of the opening. The result is an internal pocket formedwithin the spherical member 414 that is sized to accommodate the sleeve450 therein as shown in FIG. 15. Lands formed by the reduced diameternear each end of the spherical member 414 form retaining portions 460configured to receive and retain (e.g., axially) the sleeve 450 withinthe spherical member 414. Alternatively, the sleeve 450 could be securedby other methods including, but not limited to, sonic welding,interference fit, adhesive, and thermal bonding techniques. As shown inFIG. 15, teeth 453 may hold the sleeve 450 near the center of the borewhile still allowing the sleeve to expand, e.g., when the guide cannula(described below) is inserted.

Once assembled, the spherical member 414 may be pressed into the socket410 of the base 402 such that it is restrained from all but rotationabout the three mutually perpendicular axes (see FIG. 4). The anchor 400is then ready for use in a manner similar to that already describedabove. FIG. 16 illustrates a bottom perspective view of the anchor 400illustrating the spherical member 414 assembled and located within thesocket 410, while FIG. 17 illustrates a cross-sectional view of theanchor 400 after the lead 102 trajectory is fixed. In a manner similarto the anchor 200, the anchor 400 may include a lock member (e.g., screw438) to lock or immobilize the spherical member 414 relative to the base402 as shown.

By utilizing a different component/material for the device contact area424 and the spherical surface 416, the spherical member 414 may offeradvantages similar to those already described with respect to the member314 (e.g., a single spherical member could accommodate multiple sleeves(and thus multiple medical devices) of different materials and/ordiameters; different materials may be utilized for the sleeve versus thespherical surface 416).

FIGS. 18-23 illustrate an exemplary surgical lead implant procedure thatmay be used with the anchor 400 described above. However, it is notedthat the anchor 400 and lead are illustrative only as the method isgenerally applicable to the implantation of either a catheter or leadusing any of the anchor embodiments described herein (i.e., the methodwould be similar for implantation using the anchor 200).

After forming the burr hole 110 in the skull 111, a guide cannula 124may be attached to a headframe guide adapter 126 of the stereotacticapparatus 103 (see FIG. 1). The stereotactic apparatus 103 may then beconfigured such that the guide cannula 124 aligns with the burr hole 110and the target tissue location 119 within the brain 116. That is, theguide cannula 124 may be configured such that its axis (i.e., theintended medical device trajectory 118) intersects with the targettissue location 119 as shown in FIG. 18. The anchor 400 (or 200) maythen be slid over a distal end of the guide cannula 124 (i.e., thedistal tip may be inserted through the bore 418 of the spherical member414) and slid upwardly (e.g., in the direction 127) toward the guideadapter 126 before the distal end of the guide cannula is inserted intothe burr hole 110. The guide cannula 124 may then be advanced until thedistal end of the guide cannula is inside the burr hole and at or near asurface of the dura as shown in FIG. 18.

Regardless of the configuration of the spherical member (e.g.,regardless of whether the member 214, 314, or 414 is used), the bore isconfigured to expand/deform sufficiently to permit sliding entry of theguide cannula 124. The friction between the bore of the spherical memberand the guide cannula 124 is preferably sufficient to provide someresistance to unintended gravitational sliding of the anchor toward theburr hole.

At this point, the surgeon may slide the anchor 400 (or 200) down theguide cannula 124 toward the skull 111 surface as represented bydirectional arrow 128. The base 402 may then be rotated about thespherical member 414 until the base sits flush to the tissue (skull 111)surface as shown in FIG. 19.

In instances where the spherical member includes a recess on itsspherical surface (e.g., a recess 340 as provided with the sphericalmember 314), the base (e.g., 302) and/or spherical member (e.g., 314)may also be rotated about the spherical member until the recess alignswith the groove (e.g., groove 220) formed in the base (e.g., base 202).

Once the base is flush to the skull, the base may be secured to tissue,e.g., using the bone screws 403 (or 203) as shown in FIG. 20. At thispoint, the spherical member (e.g., member 214, 314, or 414) may belocked or immobilized relative to the base (e.g., base 202 or 402) usingthe lock member (e.g., screw 238 or 438). That is, the screw may beturned until it threadably penetrates (e.g., self-taps) the sphericalmember and locks the latter relative to the base as shown in FIG. 21.The anchor is then locked such that the bore (e.g., bore 418) iscoincident with the trajectory 118.

The guide cannula 124 may then be advanced until its distal end is at ornear the target tissue location 119 as shown in FIG. 22. The lead 102(or catheter) may then be inserted into the guide cannula 124 inaccordance with known techniques until the therapy delivery tip 108 ofthe device 102 is at the target tissue location 119.

When the medical device has been positioned, the guide cannula 124 maybe withdrawn or retracted (moved in the direction 130) as shown in FIG.23 while holding the device 102 in place, e.g., with a stylet (notshown) and the stereotactic apparatus 103 (see FIG. 1). As the guidecannula 124 retracts beyond the bore (e.g., beyond the sleeve 450 of thebore 418 of the spherical member 414), the elastomeric properties of thespherical member/bore immediately contract to compress against the outerdiameter of the medical device 102 as indicated in FIG. 23. That is, thesecuring of the medical device 102 along the trajectory 118 is immediateand automatic upon cannula withdrawal. Moreover, the resultingcompression (radial) retention force applied to the medical device 102is sufficient to secure the medical device relative to the anchor 200while the device is implanted.

In the illustrated embodiment, the bore of the spherical member mayexpand sufficiently to accept the guide cannula 124 (which may, in oneembodiment, be about 1.7 mm in diameter), and then immediately contractto contact and immobilize the medical device 102 (which may, in oneembodiment, be about 1 to 1.3 mm). As a result, the frictionalcompression force applied against the guide cannula by the sphericalmember may be substantially higher that that provided to the medicaldevice. In one embodiment, a lubricous coating, such aspolytetrafluoroethylene (PTFE), may be applied to the guide cannula 124to permit insertion/withdrawal of the cannula from the spherical member.

In the case of the lead 102 (or direct connection of the therapycatheter to the therapeutic source), the guide cannula may next beseparated entirely from the lead, after which the lead may be bent(after stylet removal) until it lies within the groove 420 as shown inFIGS. 13 and 14 or is otherwise adjacent to the upper side of the base.The optional cap 405 may then be attached to the base 402 (see FIG. 13)and the lead (or therapy catheter) attached to the therapy source 106(see FIG. 1).

Alternatively, in the case of catheter implantation, the catheter may becut (e.g., about 25 mm) above the anchor 200 after stylet removal. Withreference to FIG. 4, the catheter 102 may then be folded over and placedinto the groove 220 where a final cut may be made at or near the relief222. The first end 226 of the connector 204 may then be manuallyinserted by the surgeon into the lumen of the cut therapy catheter 102.The connector 204 may then be pressed into the groove 220 until it locksin place with a snap-fit. The delivery catheter 104 may then beconnected to the second end 228 of the connector 204 as shown in FIG. 4.

FIGS. 24-28 illustrate an infusion system incorporating an anchor system501 having a cranial burr hole anchor 500 in accordance with still yetanother embodiment of the invention. Once again, those of skill in theart will recognize similarities between the anchor 500 and thosedescribed elsewhere herein (e.g., the anchors 200 and 400), and thatvarious components of the different embodiments described andillustrated herein could be substituted among one another to yield yetadditional embodiments without departing from the scope of theinvention.

The anchor 500 may be designed specifically for use in anchoring atherapy catheter 102 rather than a lead. With reference primarily toFIGS. 24 and 25, the anchor 500 may again include an annular base 502that may be positioned to surround the burr hole 110 (covered by theanchor in FIG. 24, but see FIG. 25). The anchor 500 (e.g., the base 502)is operable to secure to the tissue, e.g., to an outer surface of thebone (skull 111), surrounding the burr hole 110 via any acceptablemethod. In the illustrated embodiment, the base 502 is secured with bonescrews 503 extending through openings (e.g., holes 506) formed throughthe base 502 and threaded into the skull 111. The holes 506 may beformed in portions 523 of the base 502 that protrude upwardly relativeto the remainder of the base as shown. Such a construction may provideadvantages as further described below.

The base 502 may include an upper side 507, a lower side 509, aperipheral or outer edge 511, and an inner edge 513. The inner edge 513may define an opening 508 passing through the base 502 between the upperand lower sides 507 and 509, wherein the inner edge further defines asocket 510. The socket 510 may be configured to receive therein aretention member that forms or otherwise includes a convex or sphericalsurface 516 (see FIG. 25). In the embodiment illustrated in FIGS. 24-28,the retention member may, once again, form a ball-shaped or sphericalmember 514. The retention member (e.g., spherical member 514) isconfigured to be received within the socket 510 such that the retentionmember is operable, under certain circumstances, to rotate therein aboutthree mutually perpendicular axes (see, e.g., axes x, y, and z of FIG.4).

As with the spherical members 214, 314, and 414 described above, thespherical member 514 may include a bore 518. The bore 518 is configuredto permit passage of the therapy catheter 102 through the base 502 fromthe upper side 507 to the lower side 509 as shown in FIG. 25. While theillustrated embodiment incorporates a low-profile base 502 such that anuppermost surface 515 of the spherical member 514 protrudes above thebase (see FIG. 25), such a configuration is not limiting. For example,the base 502 could be configured with greater depth (or the sphericalmember 514 could seat lower in the base) such that the uppermost surface515 is at an elevation at or below the upper side 507.

As shown in FIG. 25, the opening 508 may again be positioned to aligncoaxially with the burr hole 110. Moreover, the anchor 500 may alsoinclude a connector 504 that, like the connectors 204 and 404 describedherein, may permit fluid connection between the therapy catheter 102 andthe delivery catheter 104 as further described below. However, unlikethe connectors 204 and 404, the connector 504 may locate directly to theretention member 514, e.g., in the bore 518. As a result, there is noneed to accommodate the connector 504 or the delivery catheter 104 via agroove on the upper side 507 of the base 502 (e.g., any grooveequivalent to the grooves 220, 420 may be optional on the base 502).

Suitable biocompatible materials for the base 502, spherical member 514,and connector 504 may be similar to the like components alreadydescribed herein above with respect to the anchor 200.

The spherical member 514 may be pressed into the socket 510 of the base502 such that it is restrained from all but rotation about the threemutually perpendicular axes (see, e.g., x, y, and z axes of FIG. 4). Thespherical member 514 (as well as the base 502) may thus function in amanner similar to the spherical members 214, 314, and 414 alreadydescribed herein. However, the actual construction of the sphericalmember 514 may differ to accommodate the connector 504 as furtherdescribed below. One of skill in the art will, once again, realize thataspects of the various spherical members (e.g., 214, 314, 414, 514, andthose described below) may be substituted for one another withoutdeparting from the scope of the invention.

As shown in FIG. 25, the bore 518 is formed through the spherical member514 and is sized, in one embodiment, such that the therapy catheter 102is received therein with clearance or minimal interference. That is, inone embodiment, the bore 518 does not compressively engage the catheter.

As shown in FIG. 26, the connector 504 may form a right angle memberconnecting the therapy catheter 102 to the delivery catheter 104. Assuch, it includes a first end 526 defining a therapy tip, and anopposite or second end 528 defining a delivery tip. A longitudinal axisdefined by the first end is, in the illustrated embodiment, normal to alongitudinal axis defined by the second end as shown. The connector 504may further include an enlarged central portion 530 between the firstand second ends. The first and second ends 526,528 (e.g., the therapytip and the delivery tip) may be configured for insertion into lumensof, respectively, the therapy catheter 102 and the delivery catheter104. The shape and size of the first and second ends of the connector504, as well as the size and material of the catheters, may be selectedto produce a relatively secure and leak-free connection between thecatheters and the connector when joined. As with the connector 204, theconnector 504 is hollow to permit passage of fluid from the deliverycatheter 104 to the therapy catheter 102.

The central portion 530 of the connector 504 may be sized to be receivedwithin the bore of the spherical member 514 such that the connectorseats within the spherical member. That is (as further described below),the first end 526 of the connector 504 may be inserted into the bore 518and pushed (downwardly in FIG. 25) until the central portion 530 seatsagainst a stop surface of a counterbore or relief 527 formed in thebore. As the first end 526 of the connector 504 enters the bore 518, itmay slide into the lumen of the therapy catheter 102 as shown in FIG.25. As further described below, the spherical member 514 may includeengagement tabs 521 (see FIG. 24) that securely receive the second end528 of the connector 504 (e.g., with a snap-fit) once the first end 526and central portion 530 are fully engaged with the bore 518. Once theconnector 504 is received in this manner, it is immobilized, relative tothe spherical member 514. The anchor 500 provides the additionaladvantage in that it aligns the connector 504 (e.g., first end 526) withthe catheter trajectory 118, further reducing or eliminating biasingforces on the therapy catheter 102 in a lateral direction.

As with the anchors described elsewhere herein, the retention member 514may be immobilized relative to the base 502 using one or more lockmembers, an example of which is illustrated in FIGS. 27 and 28 (althoughlock members such as those already described herein may certainly beused with the anchor 500). Unlike the anchors 200 and 400, the anchor500 may incorporate a lock pin 538 associated with one or more of thebone screws 503. The lock pins 538 may be located within a passageway535 that extends from the holes 506 of the base 502 to the opening 508(e.g., through the inner edge 513). Each lock pin 538 may include a pinend 537 configured to selectively protrude from the base into the socket510 and penetrate the spherical member 514 to lock the spherical memberrelative to the base 502. To activate the lock pin 538, an engagementend 539 of the lock pin may protrude into the opening 506. As the bonescrew 503 associated with the opening 506 is tightened, a bevel 541formed on the screw contacts the engagement end 539 of the lock pin andtranslates the lock pin along the passageway 535 towards the sphericalmember 514. The lock pin 538 and bevel 541 may be configured to ensurethat, once the bone screw 503 is fully tightened, the pin end 537 haspenetrated the spherical member 514 adequately to lock the sphericalmember in place, but does not penetrate into the bore 518. Those ofskill in the art will realize that this pin locking mechanism may beutilized with other anchor base embodiments (e.g., anchors 200 and 400)described herein.

With reference to FIGS. 29-34, an exemplary surgical catheter implantprocedure using the anchor 500 is now described. After forming the burrhole 110 in the skull 111, a guide cannula 124 may be attached to aheadframe guide adapter (see, e.g., headframe adapter 126 ofstereotactic apparatus 103 in FIG. 18 already described herein), whereinthe stereotactic apparatus 103 may be configured such that the guidecannula 124 aligns with the target tissue location 119 within the brain116. That is, the guide cannula 124 may be configured such that its axis(i.e., the intended medical device trajectory 118) intersects with thetarget tissue location 119 as shown in FIG. 18. The anchor 500 may thenbe slid over a distal end of the guide cannula 124 (i.e., the distal endmay be inserted through the bore 518 of the spherical member 514) andslid towards the guide adapter 126 before the distal end of the guidecannula is inserted into the burr hole 110. The guide cannula 124 maythen be advanced until the distal end of the guide cannula is at or neara surface of the dura (see, e.g., FIG. 18).

Prior to advancing the guide cannula 124 to the dura, the surgeon mayengage an elastomeric member, e.g., O-ring 542, such that it stretchesto extend around the guide cannula 124 on the lower side of thespherical member 514 and connects to a retaining pin 544 secured to atop side of the spherical member as shown in FIG. 29. The sphericalmember 514 may define a series of grooves to accommodate the O-ring 542as shown in FIG. 29 (note that remainder of anchor is removed in FIG. 29to better illustrate the O-ring and its routing). The O-ring 542 mayprovide sufficient tension to hold the guide cannula 124 against a sideof the bore 518 of the spherical member 514, while still permittingrelative sliding movement of the guide cannula relative to the bore.

The surgeon may then slide the anchor 500 down the guide cannula 124until the anchor seats on the skull 111 surface (see, e.g., FIG. 19).Once the base 502 is flush to the skull, the base may be secured totissue, e.g., to the skull 111, using the bone screws 503. As describedabove, the bone screws not only secure the base to the tissue (skull111), they also actuate the lock pins 538 (see FIG. 28) as alreadydescribed herein to immobilize the spherical member 514 relative to thebase 502. That is, tightening of the bones screws 503 causes each lockpin 538 to penetrate the spherical member 514 and immobilize the latterrelative to the base 502 such that the bore 518 is aligned with thetrajectory 118.

The guide cannula 124 may then be advanced until the distal end is at ornear the target tissue location 119 as already described herein (see,e.g., FIG. 22). The therapy catheter 102 may then be inserted into theguide cannula 124 in accordance with known techniques until the deliverytip 108 of the therapy catheter is at the target tissue location 119.

When the therapy catheter 102 has been positioned, the guide cannula 124may be retracted (moved in the direction 130) as shown in FIG. 30 whileholding the catheter in place, e.g., with a stylet (not shown) and thestereotactic apparatus 103 (see FIG. 1). As the guide cannula 124retracts beyond the O-ring 542, the elastomeric properties of the O-ringcause it to immediately contract to pull the catheter 102 against thebore 518 as indicated in FIG. 31. The force applied to the catheter 102by the O-ring 542 is again sufficient to secure the catheter relative tothe anchor 500 during the remainder of the surgical procedure.

With the catheter 102 retained in the spherical member 514, the portionof the catheter protruding outwardly beyond the relief 527 (see FIG. 25)may be trimmed. The first end 526 of the connector 504 may then beinserted from above (e.g., in the direction 545), by the surgeon intothe bore 518 where it ultimately enters the lumen of the now-trimmedfirst end of the catheter as shown in FIG. 32 (the O-ring 542 may holdthe catheter 102 in place during connector 504 insertion). Oncecompletely inserted, the central portion 530 of the connector 504 mayseat within the relief 527 of the spherical member 514 as also shown inFIG. 32. Moreover, at the same time, the second end 528 of the connector504 may engage, e.g., with a snap-fit, the engagement tabs 521 formed onthe spherical member 514 as shown in FIG. 33. As a result, the catheter102 and the connector 104 are secured relative to the spherical member514, which is, in turn, secured to the base 502 by the lock pins 538(e.g., see FIG. 28).

At this point, the O-ring 542 may be cut and the O-ring and retainingpin 544 removed as shown in FIG. 34. The delivery catheter 104 may thenbe attached to the second end 528 of the connector 504 as shown. Beforeor after attachment of the delivery catheter 104, the opposite end ofthe delivery catheter may be tunneled and connected to the therapeuticsource, e.g., implantable pump 106 as shown in FIG. 1.

FIGS. 35-37 illustrate an anchor system 601 having an anchor 600 inaccordance with yet another embodiment of the invention. Once again, theanchor 600 may include an annular base 602 that may be positioned tosurround the burr hole 110 (see FIG. 37). The anchor 600 (e.g., the base602) is operable to secure to the tissue, e.g., to an outer surface ofthe skull 111, surrounding the burr hole 110, via any acceptable method.In the illustrated embodiment, the base 602 is secured with bone screws(not shown) extending through openings (e.g., holes 606) formed throughthe base 602 and threaded into the skull 111.

The base 602 may include an upper side 607, a lower side 609, aperipheral or outer edge 611, and an inner edge 613. The inner edge 613may define an opening 608 passing through the base 602 between the upperand lower sides 607 and 609, wherein the inner edge further defines asocket 610. The opening 608 may again be positioned to align coaxiallywith the burr hole 110. While not shown, an optional cap or cover mayattach to the upper side 607 of the base 602 to cover the opening 608after the medical device 102 is implanted.

The socket 610 may be configured to receive therein a retention member614 that forms or otherwise includes a convex or spherical surface 616.The retention member 614 is configured to be received within the socket610 such that the retention member is operable, under certaincircumstances, to rotate therein about three mutually perpendicular axes(see, e.g., axes x, y, and z of FIG. 4) as already described herein. Aswith the anchor 200, most any biocompatible material is suitable for thebase 602, e.g., moldable thermoplastic (e.g., polysulfone or PEEK) ormetal such as grade 2 or grade 5 Titanium.

The retention member 614 (as well as the base 602) may function in amanner substantially identical to the spherical members 214, 314, 414,and 514 already described herein. However, the actual construction ofthe retention member 614 may differ somewhat from the other retentionmembers described herein in that the member 614 forms a truncatedsphere. That is, the retention member 614 is truncated in that it has anuppermost surface 615 (when oriented as shown) forming a planar surfaceand, in one embodiment, a flat and parallel lower surface 617 as shownin FIGS. 36 and 37. However, as the retention member 614 hassubstantially spherical surfaces 616 that engage the socket 610 in amanner similar to the other retention members described herein, thetruncated retention member can also be said to form a spherical member.In fact, aspects of the various spherical members 214, 314, 414, and514, may be substituted with the spherical member 614, and vice versa,without departing from the scope of the invention.

As with the spherical members 214, 314, 414, and 514 described above,the spherical member 614 may include a bore 618 formed therethrough. Thebore 618 is configured to permit passage of the medical device (e.g.,catheter or lead 102, not shown) through the base 602 from the upperside 607 to the lower side 609. Moreover, the spherical member 614 maybe positioned within the socket 610 such that the flat upper surface 615of the spherical member is at an elevation at or below the upper side607 of the base as best seen in FIG. 37. Such a low-profile constructionmay better accommodate a relatively flat cover (not shown) if desired.

Because the spherical member 614 incorporates the parallel planarsurfaces 615, 617, it may accommodate two or more bores 618. Forexample, in the illustrated embodiment, the retention member 614 mayinclude an array of nine bores arranged in a three-by-three square. Thebores (i.e., longitudinal axes of the bores) may be parallel to oneanother and each may extend from the upper surface 615 through the lowersurface 617. By providing multiple bores 618, the surgeon may have moreoptions for catheter placement through the burr hole 110. For example,it may be beneficial to provide bores laterally spaced from thegeometric center of the spherical member to allow the medical device tobe located off-center in the burr hole. Such flexibility is provided inaddition to the trajectory-matching spherical movement already describedherein above with respect to the previously described embodiments(although it is noted that the benefit of selecting one of the outermostbores 618 may be somewhat offset by the reduced angular flexibilityafforded in device trajectory).

While shown with a square array of bores 618, such a configuration isnot limiting. For example, in an alternative embodiment, the sphericalmember 614 may have a group of bores extending across a diameter of thespherical member. In this instance, the spherical member 614 may berotated until one of the bores 618 is in the desired catheter or leadlocation. Moreover, while the bores 618 are illustrated as being normalto the surface 615, one or more of the bores could, alternatively, beangled relative to the surface 615.

In most other respects, the anchor 600 may operate in a manner similarto the other anchors already described herein. For example, the upperside 607 of the base 602 may define a passage, e.g., groove 620 (seeFIG. 35), extending from the inner edge 613 to and through the outeredge 611. The groove 620 may define a passage configured to receivetherein the medical device (e.g., catheter 102) as already describedherein. Moreover, the spherical member 614 may be immobilized relativeto the base 602 via a lock member (e.g., screw 238 (not shown) asalready described above with reference to the anchor 200) or,alternatively, the anchor 600 could be configured to provide sufficientfriction between the socket 610 and the spherical member to effectivelyimmobilize the latter during surgery and subsequent device implantation.Similarly, the bores 618 could be sized, and/or the material of thespherical member 614 selected, to provide the desired frictionalengagement to effectively immobilize the catheter 102 relative to theretention member. Potential materials for the spherical member 614include silicone, urethane, and the like.

An exemplary surgical procedure using the anchor 600 is evident from theprocedures already described herein with regard to anchor 400 (see e.g.,FIGS. 18-23). Accordingly, no further description is provided.

FIGS. 38-42 illustrate an anchor system 701 including an anchor 700 inaccordance with still yet another embodiment of the invention. Those ofskill in the art will recognize similarities between the anchor 700 andthose described elsewhere herein, and that components of the embodimentsdescribed and illustrated herein may again be substituted among thevarious embodiments to yield yet other embodiments without departingfrom the scope of the invention.

The anchor 700 is described and illustrated in the context of an anchorfor an electrical lead 102. However, as with other embodiments describedherein, such an application is exemplary only, e.g., the anchor 700could also be used to anchor a therapy catheter 102 (see, e.g., FIGS. 56and 57).

The anchor 700 may include an annular base 702 that may be positioned tosurround the burr hole 110 (covered by the anchor in FIG. 38, but seeFIG. 39). The anchor 700 (e.g., the base 702) is operable to secure tothe tissue, e.g., to an outer surface of the bone (skull 111),surrounding the burr hole 110 via any acceptable method. In theillustrated embodiment, the base 702 is secured with bone screws 703extending through openings (e.g., holes 706) formed through the base 702and threaded into the skull 111. In the illustrated embodiment, theholes 706 are formed in portions 723 of the base 702 that protrudeoutwardly as shown in FIG. 38.

The base 702 may include an upper side 707, a lower side 709, aperipheral or outer edge 711 (see FIG. 39), and an inner edge 713 (seealso FIG. 39). The inner edge 713 may define an opening 708 passingthrough the base 702 between the upper and lower sides 707 and 709,wherein the opening/inner edge further defines a socket 710 as is alsoshown in FIGS. 40-42. An optional cap or cover 705 may attach to thebase 702 (e.g., to the upper side) after the medical device 102 isimplanted. Even with the optional cap, the anchor 700 (and anchors 800and 900 described below) may have a very patient-friendly, low profile,e.g., a height of about 2 mm.

The socket 710 may be configured to receive therein a retention memberthat forms or otherwise includes a convex or spherical surface 716 (seeFIG. 39). In the embodiment illustrated in FIGS. 38-42, the retentionmember may once again form a ball-shaped or spherical member 714. Theretention member (e.g., spherical member 714) is configured to bereceived within the socket 710 such that the retention member isoperable, under certain circumstances, to rotate therein about threemutually perpendicular axes (see, e.g., axes x, y, and z of FIG. 4).

As with the spherical members 214, 314, 414, 514, and 614 describedabove, the retention member 714 may include a bore 718 formedtherethrough. The bore 718 is configured to permit passage of themedical device (e.g., catheter or lead 102) through the base 702 fromthe upper side 707 to the lower side 709. Moreover, once again, thespherical member 714 may be positioned within the socket 710 such thatan uppermost surface 715 of the retention member is at an elevation ator below the upper side 707 of the base as best seen in FIG. 39. Such aconstruction may better accommodate the cap 705.

As further shown in FIG. 39, the opening 708 may again be positioned toalign coaxially with the burr hole 110. Moreover, the upper side 707 ofthe base 702 may define a passage extending from the inner edge 713 toand through the outer edge 711 as best illustrated in FIGS. 40-41. Thepassage may define a channel configured to receive therein the medicaldevice (e.g., lead 102) as described in more detail below. The passagemay be devoid of features, or could incorporate features useful tocapturing a catheter connector such as connector 204, as described andillustrated herein.

In the illustrated embodiment, the passage is defined by a slot 720extending radially from the socket through the outer edge and passingcompletely through the upper and lower sides 707, 709 as shown in FIGS.40-41. Such a construction yields a split base 702 having a first sideor portion 731 and a second side or portion 733 (also referred to hereinas spaced-apart first and second portions), i.e., the base may form aU-shaped or C-shaped member when viewed from above. The splitconfiguration is advantageous as it permits the effective diameter ofthe opening 708 to change merely by displacing the first portion 731relative to the second portion 733 (e.g., selectively moving the firstand second portions closer to (or farther away from) one another). Forexample, in the illustrated embodiment, the base 702 may form a slot 720having a first width 746 corresponding to the anchor/base being in afirst, e.g., expanded, configuration (see FIG. 40), and a second width748 corresponding to the anchor/base being in a second, e.g., locked,configuration (see FIG. 41), wherein the second width is less than thefirst width. Once again, reducing the width of the slot 720 causes acorresponding reduction in the diameter of the socket 710. As a result,the spherical member 714 may be effectively clamped or squeezed bycollapsing the split base 702 as described herein. As with the otheranchors described herein, most any biocompatible material is suitablefor the base 702, e.g., moldable thermoplastic (e.g., polysulfone orPEEK) or metal such as grade 2 or grade 5 Titanium. The spherical member714 (as well as the members 814 and 914 described below), however, maybe made from a soft, elastomeric material, e.g., silicone or urethane,for reasons further described below.

The spherical member 714 may function in a manner similar to thespherical members 214, 314, 414, 514, and 614 already described herein.In fact, as stated elsewhere, the various spherical members describedand illustrated herein may be substituted for one another in otherembodiments of the bases described herein without departing from thescope of the invention.

As shown in FIG. 39, the spherical member 714 may have a single bore 718therein and it may function in a manner similar to the other retentionmembers already described herein. However, instead of immobilizing thespherical member with a screw 238 or lock pin 538, the spherical member714 may be immobilized via compression of the socket 710. Moreover, thespherical member 714 and bore 718 may be selected/sized to ensure thatcompression of the socket 710 also results in compression against theouter surface of the medical device 102 with sufficient force toimmobilize the device relative to the spherical member.

To achieve reconfiguration of the base between the first, expanded(e.g., open) configuration (see FIG. 40) and the second, lockedconfiguration (see FIG. 41), the anchor may include a lock mechanism 738as perhaps best viewed in the bottom perspective view of FIG. 42. Asshown in this view, the lock mechanism 738 may be configured to collapsethe socket 710 to immobilize both: the spherical member 714 relative tothe base 702; and the medical device 102 relative to the sphericalmember.

In the illustrated embodiment, the lock mechanism 738 is configured asan arm 762 connecting the first portion 731 to the second portion 733 ofthe base 702 by spanning across the slot 720. A first end 764 of the arm762 is attached or connected (e.g., pivotally) to the first portion 731,while a second end 766 of the arm is attached or connected (e.g.,pivotally) to the second portion 733 (e.g., to a cam or cam mechanism768 attached to the second portion). The cam 768 may include toolfeatures, e.g., a screw head 770 as shown in FIGS. 40-41, that permitsthe surgeon to manipulate the cam to collapse the socket 710 as furtherdescribed below. That is to say, the cam mechanism may selectivelydisplace, via the arm, the first portion 731 of the base relative to thesecond portion 733. The base 702 and/or cam 768 may also include indicia772 (see FIG. 41), to visually indicate to the surgeon when the cam hasbeen fully actuated, e.g., when the base has moved to its second, lockedconfiguration shown in FIG. 41. In the illustrated embodiment, theindicia include marks on the screw head 770 and corresponding marks onthe base than may align when the cam 768 is in a position correspondingto the base being in the first, expanded configuration and/or thesecond, locked configuration. The screw head 770 may rotate about 180degrees between the first, expanded configuration and the second, lockedconfiguration. To prevent the surgeon from over-compressing the socket710, one or both of the first and second portions 731, 733 may includecontacting stop members or surfaces 774 (see FIG. 42) that limitmovement of the first portion the base 702 toward the second portionbeyond the locked configuration.

The anchor 700 may ship with the base 702 in the first, expandedconfiguration shown in FIG. 40. In this configuration, the socket andspherical member are in an uncompressed state. That is, little or nocompression is applied by the socket 710 on the spherical member 714. Inone embodiment, the compression on the spherical member in theuncompressed state may be sufficient to ensure that the bore 718frictionally engages the guide cannula 124 as further described below,but is not so excessive that it prevents sliding along the cannula or soexcessive that the retention member 714 cannot rotate within the socket(e.g., about the three mutually perpendicular axes shown in FIG. 4).During implantation, however, when the cam is rotated 180 degrees fromthe position shown in FIG. 40 (corresponding to the base being in thefirst, expanded configuration) to the position shown in FIG. 41(corresponding to the base being in the second, locked configuration),the socket 710 and spherical member 714 reconfigure to a compressedstate. In the compressed state, the socket 710 applies sufficientcompression to the spherical member 714 to compress the medical device102 by reducing the bore 718 to effectively immobilize the devicerelative to the spherical member. Moreover, the socket 710 compressessufficiently to effectively immobilize the spherical member 714 (withinthe socket 710) relative to the base.

FIGS. 43-49 diagrammatically illustrate an exemplary surgical leadimplant procedure that may be used with the anchor 700 described above.Once again, the anchor 700 and lead 102 are illustrative only as themethod is also applicable to the implantation of a catheter.

After forming the burr hole 110 in the skull 111, a guide cannula 124may be attached to a headframe guide adapter 126 of the stereotacticapparatus 103 (see FIG. 1). The stereotactic apparatus 103 may beconfigured such that the guide cannula 124 aligns with the target tissuelocation 119 within the brain 116. That is, the guide cannula 124 may beconfigured such that its axis (i.e., the intended medical devicetrajectory 118) intersects with the target tissue location 119 as shownin FIG. 43. The anchor 700 (configured in the first, expandedconfiguration) may then be slid over a distal end of the guide cannula124 (i.e., the distal end may be inserted through the bore 718 of thespherical member 714) and slid upwardly toward the guide adapter 126before the distal end of the guide cannula is inserted into the burrhole 110. The guide cannula 124 may then be advanced until the distalend of the guide cannula is at or near a surface of the dura as shown inFIG. 43. The bore 718 of the spherical member 714 is, once again,sufficiently elastic to expand/deform to permit sliding entry of theguide cannula 124. The friction between the bore 718 and the guidecannula 124 is preferably sufficient to provide some resistance tounintended falling of the anchor toward the burr hole.

At this point, the surgeon may slide the anchor 700 down the guidecannula 124 toward the skull 11 surface as represented by arrow 128 inFIG. 43. The base 702 may then be rotated about the spherical member 714until the base sits flush to the tissue (skull 111) surface as shown inFIG. 44.

Once the base 702 is flush to the skull surface, the base may be securedto tissue, e.g., using two of the three bone screws 703 as shown in FIG.45. One bone screw on one side (e.g., closest to the first side 731) ofthe slot 720 is not attached at this point to permit the base 702 todeflect to the second, locked configuration (see FIG. 41). The guidecannula 124 may then be advanced until its distal end is at or near thetarget tissue location 119. The lead 102 (or catheter) may then beinserted into the guide cannula 124 in accordance with known techniquesuntil the therapy delivery tip 108 of the device 102 is at the targettissue location 119.

When the medical device 102 has been positioned, the guide cannula 124may be retracted (moved in the direction 130) as shown in FIG. 46 whileholding the catheter in place (e.g., with a stylet attached to thestereotactic apparatus 103 (see FIG. 1)). As the guide cannula 124retracts beyond the bore 718, the elastomeric properties of thespherical member 714 cause the bore 718 to reduce in diameter. However,some clearance between the spherical member 714 and the device 102 maystill exist, at least while the spherical member is in the uncompressedstate. The stylet (not shown) may hold the medical device in placeduring cannula retraction.

The surgeon may, at this point, rotate the screw head 770 of the cam 768until the indicia 772 align as shown in FIG. 47. As the cam rotates, thebase 702 moves from the first, expanded configuration of FIG. 40, to thesecond, locked configuration shown in FIG. 41. This movement resultsfrom the cam mechanism displacing the second end 766 of the arm from afirst position corresponding to the expanded configuration of the base,to a second position corresponding to the locked configuration of thebase. Once again, in this second, locked configuration, the socket 710collapses sufficiently to compress the spherical member 714 against themedical device 102, immobilizing the medical device relative to thespherical member. Moreover, the spherical member 714 is compressed bythe socket 710, immobilizing the spherical member relative to thesocket/base. The medical device 102 is thus immobilized relative to thebase 702.

The stylet (not shown) may then be removed from the medical device 102and the device bent and laid into the slot 720 as shown in FIG. 48(i.e., the slot width is preferably selected to receive the medicaldevice when the base is in the locked configuration). The optional cap705 may then be attached to the base 702 and the medical device 102attached to the therapy source 106 (see FIG. 1). The last screw 703 maythen be inserted to secure the base in the second locked configurationas shown in FIG. 48.

In the illustrated embodiment, the cap 705 may be attached by engaging atab 771 with a hook 773 on the base 702 (see FIG. 48) and thenstretching the cap until slots 769 (see FIG. 49) formed in the capengage tabs 767 of the first and second portions of the base. The cap705 may be made of an acceptably stretchable material such as silicone.Alternatively, the cap could be rigid and rely on elongation of theportion of the cap containing the tabs 771 to accommodate attachment tothe base.

FIGS. 50-55 illustrate an anchor system 801 including an anchor 800 inaccordance with still yet another embodiment of the invention. Those ofskill in the art will recognize similarities between the anchor 800 andthe anchor 700 described above. In fact, in one embodiment, the anchor800 differs from the anchor 700 only with respect to the lock memberused to secure the anchor base in the second, locked configuration. Oneof skill in the art will appreciate that components of the anchor 800may be substituted with components of the other embodiments describedherein, and vice-versa, to produce yet additional embodiments withoutdeparting from the scope of the invention.

The anchor 800 is, like the anchor 700, described and illustrated in thecontext of an anchor for an electrical lead 102. However, as alreadystated, such an application is exemplary only and the anchor 800 couldalso be used to anchor a therapy catheter 102.

The anchor 800, once again, may include an annular base 802 that may bepositioned to surround the burr hole 110 (not shown, but see FIG. 46 foranalogous view). The anchor 800 (e.g., the base 802) is operable tosecure to the tissue, e.g., to an outer surface of the skull 111,surrounding the burr hole 110 via any acceptable method. In theillustrated embodiment, the base 802 is secured with bone screws (notshown) extending through openings (e.g., holes 806) formed through thebase 802 and threaded into the skull 111. In the illustrated embodiment,the holes 806 are formed in portions 823 of the base 802 that protrudeoutwardly as shown in FIG. 50.

The base 802 may include an upper side 807, a lower side 809, aperipheral or outer edge 811, and an inner edge 813. The inner edge 813may define an opening 808 passing through the base 802 between the upperand lower sides 807 and 809, wherein the inner edge further defines asocket 810. The optional cap or cover 705 may attach to the base 802 tocover the opening 808 as already described above.

The socket 810 may be configured to receive therein a retention memberthat forms or otherwise includes a convex or spherical surface 816. Inthe embodiment illustrated in FIGS. 50-55, the retention member may onceagain form a ball-shaped or spherical member 814. The retention member(e.g., spherical member 814) is configured to be received within thesocket 810 such that the retention member is operable, under certaincircumstances, to rotate therein about three mutually perpendicular axes(see, e.g., axes x, y, and z of FIG. 4).

The spherical member 814 is similar in most respects to the sphericalmember 714 already described herein (e.g., the member 814 includes abore 818 sized to receive the medical device 102/guide cannula 124 insubstantially the same way). As a result, no further description isprovided herein. Moreover, the base 802 includes a passage or channel,e.g., slot 820, extending from the inner edge 813 to and through theouter edge 811 that results in a split base (forming a U-shaped orC-shaped member when viewed from above) as already described above withreference to anchor 700. As a result, no further description is providedwith respect to aspects of the anchor 800/base 802 that are common withthe anchor 700/base 702. In fact, for the most part, those itemsidentified with a reference numeral 8 xx will be similar to the sameitem identified with the number 7 xx (e.g., bore 818 is similar to bore718, retention member 814 is similar to retention member 714, etc.),unless otherwise identified herein.

As stated previously, the anchor 800 does differ from the anchor 700primarily with respect to the lock mechanism. In the anchor 700, thelock mechanism 738 includes the cam 768, while in the anchor 800, thelock mechanism is configured as a clip or clips connecting a firstportion 831 of the base 802 to a second portion 833 of the base byspanning across the slot 820 as shown in FIG. 50. A first or “open” clip868 (see FIGS. 50-53) may include one or more openings 878 that engageprotrusions or protruding ears of the first portion 831 and secondportion 832 of the base 802 to hold the base in the first, expandedconfiguration, e.g., by holding the first portion in fixed relationrelative to the second portion. The first clip 868 may also include aspacer 875 that slides into the slot 820 and prevents the first andsecond portions 731, 733 from moving towards one another.

The system 801 may also include a second or lock clip 876 (see FIG. 54)that includes a narrower opening 880 that engages the protruding ears ofthe first and second portions 831, 833 to correspondingly hold the basein a second, locked configuration (an additional clip could be providedto hold the base in another configuration between the expanded andlocked configurations if desired). The first and second portions 831,833 may again include contacting surfaces 874 (only visible on one sidein FIG. 51) that may limit the amount of compression the base 802 mayapply to the socket 810.

The anchor 800 may ship with first clip 868 attached to the base 802such that the base is in the first, expanded configuration as shown inFIG. 50. In this configuration, the socket 810/spherical member 814 arein the uncompressed state, e.g., compression on the socket 810 issufficient to ensure the bore 818 can frictionally engages the guidecannula 124 (see FIG. 53) as further described below, but is not soexcessive that the retention member 814 cannot rotate within the socket.During implantation, however, the second clip 876 may replace the firstclip 868. When this occurs, the base 802 is moved to the second, lockedposition wherein the socket 810 applies sufficient compression to theretention member 814 to compress the medical device 102 within the bore818 and effectively immobilize the device 102 relative to the sphericalmember (i.e., the socket 810/spherical member 814 moves to thecompressed state). Moreover, the socket 810 compresses sufficiently toeffectively immobilize the spherical member 814 within the socket 810.

During implantation, the anchor 800 operates using a procedure similarto that described with respect to the anchor 700. Accordingly, theprocedure described with reference to FIGS. 43-49 applies also to theanchor 800, with the following distinctions.

The anchor 800 may have attached thereto the first clip 868 as shown inFIG. 50 when it is slid over the cannula as shown in FIGS. 43 and 52.After the base 802 is moved to the skull 111 and has been secured withtwo of the three screws 806, the lead has been implanted, and the guidecannula retracted, the surgeon may remove the first clip 868 as shown inFIG. 53. The first and second portions 831, 833 may then be pinchedtogether and the second or lock clip 876 slid over the base 802 as shownin FIG. 54. With the second clip 876 so attached, the base 802 movesfrom the first, expanded configuration of FIG. 52, to the second, lockedconfiguration shown in FIG. 54. In this second configuration, the socket810 collapses sufficiently to compress the retention member 814 againstthe medical device 102, immobilizing the latter relative to the former.Moreover, the retention member 814 is compressed by the socket,immobilizing the former relative to the latter. The medical device isthus immobilized relative to the anchor 802.

The third screw 803 may then be threaded into the tissue as shown inFIG. 54, securing the base in the second configuration. Once the thirdscrew is tightened, the second clip 876 may be removed.

The stylet (not shown) may then be removed from the medical device 102and the device bent and laid into the slot 820. The optional cap 705 maythen be attached to the base 802 as shown in FIG. 55, and the medicaldevice 102 attached to the therapy source 106 (see FIG. 1). In theillustrated embodiment, the cap 705 may be attached to the base in thesame manner described herein with respect to the base 702.

FIGS. 56-57 illustrate an anchor 900 that is a variation of the anchor700 revised to accommodate anchoring of a therapy catheter 102 andconnection of the same with a delivery catheter 104. Once again, onlythose aspects that differ from the anchor 700 will be described.

As shown in FIG. 56, the anchor 900 may again include a base 902 havinga slot 920 similar to the slot 720, and a spherical member 914 containedwithin a socket 910 of the base. However, the slot 920 may include arelief 922 configured to accommodate ears or protruding portions 932 ofa central portion 930 of a connector 904 that is shown in more detail inFIG. 57. The connector 904 may include a first end 926 for fluidlycoupling to the therapy catheter 102, and second end 928 for fluidlycoupling to the delivery catheter 104.

During implantation, the anchor 900 may be moved to the second, lockedconfiguration (as shown in FIG. 56) after the therapy catheter ispositioned and the guide cannula is removed as described above withreference to the anchor 700. After stylet removal from the therapycatheter 102, the catheter may be laid into the slot 920 and cut tolength at the relief 922. The first end 926 of the connector 904 maythen be manually inserted into a lumen of the cut end of the therapycatheter 102. The connector 904 may then be placed into the slot 920,where it may be received with a clearance fit. The second end 928 of theconnector may then be connected to the delivery catheter by placing thelumen of the delivery catheter over the second end. Once the catheters102, 104 are connected, an optional cap (see, e.g., cap 705) may beattached to the base 902 as already described herein, and the deliverycatheter attached to the therapy source 106 (see FIG. 1). The cap 705may capture and retain the connector 904 in place. Moreover, the centralportion 930 of the connector 904 may reduce or prevent the transmissionof axial loads from the delivery catheter 104 to the therapy catheter102.

Burr hole anchors and systems in accordance with embodiments of thepresent invention may provide various benefits including, for example,reducing or eliminating biasing forces applied to an implanted medicaldevice that tend to result in device migration or lateral compression ofbrain tissue near the entry point. As a result, the delivering tip ofthe therapy catheter may be less likely to be displaced during theimplantation period. Such a benefit is realized regardless of devicetrajectory through the burr hole, offering greater surgical flexibilityin burr hole placement relative to target tissue location. Moreover,retention members like those described herein may also assist withholding the medical device during the remainder of the anchoring processwithout the use of specialized surgical tools. Still further,embodiments such as those described herein are well-suited toimmobilizing both leads and catheters as they achieve immobilization bycompressing the medical device along a relatively soft, elastomericcylindrically-shaped contact area as opposed to holding mechanisms thatuse a more rigid, two point contact configuration.

Yet still further, anchors and systems in accordance with embodiments ofthe present invention may be cost-effective to produce. For example, thebases and retention members described herein may be produced throughinjection molding manufacturing, permitting low cost production ofmultiple sizes (e.g., primate and human). Moreover, there is norequirement for internal anchor tubing to connect the delivery catheterto the therapy catheter. As a result, potential leak points may beavoided.

The complete disclosure of the patents, patent documents, andpublications cited in the Background, the Detailed Description ofExemplary Embodiments, and elsewhere herein are incorporated byreference in their entirety as if each were individually incorporated.

Illustrative embodiments of this invention are described and referencehas been made to possible variations within the scope of this invention.These and other variations, combinations, and modifications of theinvention will be apparent to those skilled in the art without departingfrom the scope of the invention, and it should be understood that thisinvention is not limited to the illustrative embodiments set forthherein. Accordingly, the invention is to be limited only by the claimsprovided below and equivalents thereof.

What is claimed is:
 1. A sub-dermal anchor configured to secure amedical device implanted via a portal formed in a mammalian body, theanchor comprising: a base configured to secure to tissue surrounding theportal, the base comprising an upper side, lower side, outer edge, andinner edge, the inner edge defining an opening passing between the upperand lower sides, the opening forming a socket; and an elastomericretention member comprising a spherical surface, the retention memberconfigured to be received within the socket such that the retentionmember may rotate therein about three mutually perpendicular axes, theretention member defining a bore formed therethrough, the boreconfigured to permit passage of the medical device through the base fromthe upper side to the lower side; wherein the retention member ispositioned within the socket such that an uppermost surface of theretention member is at an elevation below the upper side of the base. 2.The anchor of claim 1, wherein the upper side of the base defines apassage extending from the inner edge to the outer edge, the passageconfigured to receive therein the medical device.
 3. The anchor of claim2, further comprising a connector configured for captivation within thepassage.
 4. The anchor of claim 1, further comprising a lock memberconfigured to lock the retention member relative to the base.
 5. Theanchor of claim 1, wherein the bore of the retention member isconfigured to receive the medical device with an interference fit. 6.The anchor of claim 1, wherein the retention member comprises aball-shaped member.
 7. The anchor of claim 1, wherein the retentionmember comprises a separate sleeve defining at least part of the bore,the sleeve configured to frictionally engage the medical device.
 8. Theanchor of claim 7, wherein the retention member comprises a firstmaterial and the sleeve comprises a second material different than thefirst material.
 9. The anchor of claim 7, wherein inner surfaces of theretention member form retaining portions configured to receive andretain the sleeve.
 10. The anchor of claim 1, wherein the retentionmember comprises two semi-spherical halves.
 11. The anchor of claim 10,further comprising a cylindrical sleeve contained between the twosemi-spherical halves, wherein an inner surface of the sleeve forms thebore and is configured to frictionally receive the medical device. 12.The anchor of claim 1, wherein the retention member is truncated suchthat its uppermost surface comprises a planar surface, the planarsurface including two or more bores.
 13. A burr hole anchor configuredto secure a medical device implanted through a burr hole, the anchorcomprising: a base configured to secure to bone surrounding the burrhole, the base comprising an upper side, lower side, outer edge, andinner edge, the inner edge defining an opening passing between the upperand lower sides, wherein the opening forms a socket; and an elastomericspherical member configured to be received within the socket such thatthe spherical member may rotate therein, the spherical member defining abore formed therethrough, the bore configured to permit passage of themedical device through the base from the upper side to the lower side,the spherical member configured to immobilize the medical device viaapplication of a radial compression force applied to the medical device.14. The anchor of claim 13, wherein the radial compression force isapplied by the spherical member over a substantial portion of a lengthof the bore.
 15. The anchor of claim 13, wherein the spherical membercomprises: two semi-spherical halves comprising a first material; and asleeve comprising a second material different than the first material,the sleeve contained within the two semi-spherical halves such that atleast a portion of the bore is defined by an inner surface of thesleeve.
 16. The anchor of claim 15, wherein the sleeve is configured toengage an outer diameter of the medical device with an interference fit.17. The anchor of claim 13, wherein the upper surface of the basedefines a groove extending from the inner edge to the outer edge, thegroove configured to receive therein the medical device.
 18. The anchorof claim 17, further comprising a connector configured to be captivatedwithin the groove.
 19. The anchor of claim 13, further comprising a lockmember configured to lock the spherical member relative to the base. 20.The anchor of claim 19, wherein the lock member comprises a fastenerconfigured to protrude from the base into the opening and penetrate thespherical member.
 21. The anchor of claim 13, wherein the sphericalmember is truncated such that an uppermost surface of the sphericalmember comprises a planar surface, the planar surface including two ormore bores.
 22. A method for anchoring a medical device relative to abody portal of a patient, the method comprising: aligning a guidecannula with the body portal such that a trajectory of the guide cannulaintersects a target tissue location within the patient; inserting adistal tip of the guide cannula through a bore formed in a portal anchorand sliding the portal anchor along the guide cannula, the anchorcomprising: a base configured to secure to tissue surrounding theportal, the base comprising an upper side, lower side, outer edge, andinner edge, the inner edge defining an opening passing between the upperand lower sides, the opening forming a socket; and an elastomericspherical member configured to be received within the socket such thatthe spherical member may rotate therein about three mutuallyperpendicular axes, the spherical member defining the bore for receivingthe guide cannula; positioning the guide cannula so that the distal tipis inside the body portal; sliding the anchor towards the distal tip ofthe guide cannula until the base of the anchor reaches the tissuesurrounding the body portal; rotating the spherical member relative tothe base until the base is flush with the tissue surrounding the bodyportal; and attaching the base to the tissue.
 23. The method of claim22, further comprising immobilizing the spherical member relative to thebase.
 24. The method of claim 23, wherein immobilizing the sphericalmember relative to the base comprises tapping a screw passing throughthe base into the spherical member.
 25. The method of claim 22, furthercomprising: implanting the medical device through the guide cannula;withdrawing the guide cannula from the bore of the spherical member; andrestraining the medical device automatically via compression between thebore of the spherical member and the medical device.
 26. The method ofclaim 25, further comprising bending the medical device such that it isadjacent the upper side of the base.
 27. The method of claim 26, whereinbending the medical device comprises bending the medical device until itlies within a groove formed in the upper side of the base, the grooveextending from the inner edge to the outer edge.
 28. An infusion systemcomprising: a therapy catheter implantable through a burr hole, thetherapy catheter comprising a therapy delivery end configured to bepositioned at a target tissue location; a delivery catheter operable todeliver a therapeutic agent, from a source containing the therapeuticagent, to the therapy catheter; a connector configured to fluidly couplethe therapy catheter with the delivery catheter; and an anchorcomprising: a base configured to secure to bone surrounding the burrhole, the base comprising an upper side, lower side, outer edge, andinner edge, the inner edge defining an opening passing between the upperand lower sides, the opening forming a socket; and a spherical memberconfigured to be received within the socket such that the sphericalmember may rotate therein about three mutually perpendicular axes, thespherical member defining a bore formed therein, the bore configured toreceive both a first end of the therapy catheter and a first end of theconnector when the first end of the connector is fluidly coupled to thetherapy catheter.
 29. The system of claim 28, wherein the bore of thespherical member is configured to align with an implant trajectory ofthe therapy catheter.
 30. The system of claim 28, wherein the connectorcomprises a second end configured to fluidly couple to the deliverycatheter, wherein the first end of the connector forms an axis that isnormal to an axis of the second end of the connector.
 31. The system ofclaim 28, further comprising a lock pin configured to protrude from thebase and penetrate the spherical member.
 32. The system of claim 28,wherein the spherical member comprises tabs configured to engage theconnector when the first end of the connector is fluidly coupled to thetherapy catheter.
 33. The system of claim 28, wherein the sourcecontaining the therapeutic agent comprises an implantable infusion pump.34. An infusion system comprising: a therapy catheter implantablethrough a burr hole, the therapy catheter comprising a therapy deliveryend configured to be positioned at a target tissue location; a deliverycatheter operable to deliver a therapeutic agent, from a sourcecontaining the therapeutic agent, to the therapy catheter; a connectorconfigured to fluidly couple the therapy catheter with the deliverycatheter; and an anchor comprising: a base configured to secure to bonesurrounding the burr hole, the base comprising an upper side, lowerside, outer edge, and inner edge, the inner edge defining an openingpassing between the upper and lower sides, wherein the opening forms asocket; and an elastomeric spherical member configured to be receivedwithin the socket such that the spherical member may rotate therein, thespherical member defining a bore formed therethrough, the boreconfigured to permit passage of the therapy catheter through the basefrom the upper side to the lower side, the spherical member configuredto immobilize the therapy catheter via application of a radialcompression force applied to the therapy catheter.
 35. The system ofclaim 34, wherein the bore of the spherical member is configured toalign with an implant trajectory of the therapy catheter.
 36. The systemof claim 34, wherein the source containing the therapeutic agentcomprises an implantable infusion pump.